1/8" Thick WRC Stripper Kayak?

[sp_clark]

This stuff be too unforgiving for a kayak stripper build? (S'not me doing the planning.)

Fiberglass & epoxy on both sides of course.

Common practice being 1/4" strips (cove & bead is a worthwhile feature to employ of course) but the contemplative builder has 1/8" WRC strips in volume at hand.

Might a suitably-chosen design be possible with cold-molding two layers of these 1/8" WRC strips?

Assuming the builder has appropriate skills?

And patience?

[upchurchmr]

3/16 has been used for a standard design.
I found them very hard to keep fair, once that happened, there was not enough thickness for sanding to get fair. so I had to fill. Then I had to paint instead of clear finish.
Cove and bead would be completely useless - you couldn't accurately make a cove on a 1/8" strip.
Now think about getting perfectly smooth, fair joints ( not likely, but the best case). So now you have 3/4" flats on the surface of the hull. How much do you have to sand off the joint in order to fair the hull smooth?
Is there any glue/ wood left for strength?
I don't think you would have any left in areas of the highest curvature.

If you really want to do this, double or triple the number of frames for the mold and use 3/8 x 1/8 strips, use square edged strips, and be ready to use staples to match up the strip edges between the frames.
Why not go all the way and use 3oz cloth - It will save more weight and be more drapeable over the outside and inside of the hull.

Or, use the first 4' of the kayak molds, and make a 4' section of the boat as a test piece. If the test doesn't convince you of the impracticality of the idea, then make another 4' section using 3/4 x 1/4 strips.
Glass both test sections, let it cure 2 weeks, then destroy the test pieces. Your gonna see why 1/8 is not desirable.

How much do you think you would save in weight with 1/8 strips? I assume that is why you would do this? Or is it cost of the wood? A little hint - the cost of the wood is just about the smallest cost in the build (1/4 x 3/4 strips).

Have you tried cutting 1/8 strips? Watch out for your fingers.

Have you ever done a strip planked project?

Do a test - it wouldn't cost much. Probably 2each 2x4s. The majority of cost would be in the glass and epoxy.

Sorry to be such a wet blanket, but there are reasons why 1/4 x 3/4 is a "standard".

If you or your buddy goes ahead with 1/8 please give us a report. I'd be interested if you can do this successfully.

[JimConlin]

I’d give it some experimentation.
There were water racing canoes made of ~1/8” cedar strips, glass sheathed. Crazy light, but fragile. I don’t know whether this is still done.

I’d dust off my Gougeon Brothers book. I haven’t thought about cold molding for some years.

I’d think that 1/8” cedar strips would be too stiff to accommodate ‘thwartship curves of a kayak, but laying two layers at an acute angle between layers might yield a panel with nice properties. Going with two layers, tripped, maybe you could plane the strips a bit thinner and still get adequate stiffness.

Tighter mold spacing will be needed. Learn to enjoy lofting.

What’s the opinion of the house on using a PVA glue like Titebond III between layers?

[sp_clark]

Did a 14' Bermuda-rigged stripper scow 50 years back. 1/4" x 3/4" redwood strips, square-edged then polyester+'glass inside & out.

T'was heavy once built but it sailed well, would plane in a decent breeze with one aboard.

What I was wondering is whether WRC 1/8" strips could be coaxed into proper kayak hull shape for a two-layer 'build' that then would see 'glass on inside & out.

I know 1/4" C&B is 'standard" for strippers now; C&B came of age a couple years' after I built that scow. Makes for much easier assembly, fairing once done. Not gonna happen with 1/8" strips.

This is all conjecture, why I put it to the Forumites for their opinions.

Still, I like your idea of a test project to evaluate the techniques that might enable such thinnish strips to be coaxed into alignment then epoxified in place. If two layers can be shaped as would 1/4" strips....

(And thanks for your post upchurchmr.)

I’d give it some experimentation.
There were water racing canoes made of ~1/8” cedar strips, glass sheathed. Crazy light, but fragile. I don’t know whether this is still done.

I’d dust off my Gougeon Brothers book. I haven’t thought about cold molding for some years.

I haven't either, to be entirely above board. But the concept is intriguing in the depths of a Midwest Winter.

The fragility of a 1/8" WRC core for sandwiching between 'glass & epoxy is why I raised the thought of cold-molding a double-thickness core. End result, if doable, ought to be stiffer than what would be the result of using typical 1/4" C&B stuff, yes?

I’d think that 1/8” cedar strips would be too stiff to accommodate ‘thwartship curves of a kayak, but laying two layers at an acute angle between layers might yield a panel with nice properties. Going with two layers, tripped, maybe you could plane the strips a bit thinner and still get adequate stiffness.

I was thinking maybe soaking 'em and/or a heat gun to add some flexibility during positioning, then let dry before epoxifying into place.

Tighter mold spacing will be needed. Learn to enjoy lofting.

What’s the opinion of the house on using a PVA glue like Titebond III between layers?

TB III might speed things along but this is a 'thought exercise' for the time being so I like the idea. TB III is certainly cheaper than 2-part epoxy. Might be useful for upchurchmr's 'sectional' test project.

Thanks for your post Jim.

[Rumars]

How wide are those strips ar hand? That will decide how feasible cold molding is, since you need some width for spiling.
To cold mold you first need ribbands on the molds, tightly spaced and faired. They need to be fairly thick, 1/2 minimum in order to not deflect when you bend the veneer over them. Titebond would only work with a vacuum bag, staples don't have enough clamping force for it.

[sp_clark]

How wide are those strips at hand? That will decide how feasible cold molding is, since you need some width for spiling.

No idea. I don't know the prospective builder; my assumption would be nominal 3/4" like what I would first attempt to make use of. Also, since he was looking to learn whether 1/8" thick WRC strips would be adequate for a strip-built cored hull, I'm leaving out the traditional spiling technique for true cold-molded fabrication with wide, thin veneer. The 1/8" strips might be planed a bit as and when necessary but mostly used full-width if possible.

Titebond would only work with a vacuum bag, staples don't have enough clamping force for it.

Would TB of any kind 'cure' properly in a vacuum? Would the lack of air hinder the cure or instead decrease the time involved owing to the lower humidity of a vacuum?

My own choice would be the synthetic 18 ga. brads rather than metallic staples. I used their 1/2" brads when bonding the 4mm okoume decks for a pair of amas I built for my Waterlust canoe last winter. They worked wonderfully well for that task & don't require removal, simply a touch with a sanding block to bring them down to level if set a bit proud.

That this is to be a one-off certainly weighs heavily against doing it by cold-molding, what with the time & expense of building the requisite mold prior to beginning.

[Rumars]

If they are 3/4 or similar narrow stock (real wood edging for chipboard furniture?) the simplest way is to glue two of them together on the bench into a 1/4 strip, then proceed to build as usual. All he needs are some long clamps (or a wedge arrangement) and a sheet of plastic, then he can glue and clamp them in batches using plastic strips as a separator between each pair.

PVA glues cure by drying out, the water gets absorbed by the wood, vacuum would only speed it up.

[Todd Bradshaw]

I built this one back in the mid 1970s from 3/16" sitka spruce strips (square edged, no bead and cove) and it worked OK. To do one with 1/8" strips is possible, but you would need to be awfully careful about edge-to-edge alignment and fixing alignment problems would be a real bear. It was done by building the hull and deck sections separately and then joining them with inside and outside seams for a continuous wood look and no internal chine logs. Strip building two halves that line up that accurately is quite a challenge.

Nanaimo.jpg

[robm]

I don't think the 1/8" strips would save much weight. Reducing the thickness of the core would reduce the stiffness of the overall laminate, which might be a problem.